Well Management
Isolation Distances From a Water-Supply Well

Minnesota Rules, Chapter 4725
Rules Relating to Wells and Borings
August 4, 2008

The isolation distances below are from Minnesota Rules, chapter 4725. Distances must be measured horizontally from the water-supply well. Minnesota Statutes, section 103I.205, subdivision 6, prohibits constructing, placing, or installing an actual or potential contaminant source from a well that is less than the minimum distance prescribed by rule. The minimum isolation distances must be maintained between a new well and a contamination source no longer in use, unless all contaminant sources and contaminated soils are removed. Additional information and explanations can be found in the Rules Handbook, A Guide to the Rules Relating to Wells and Borings, or by contacting the Well Management Section.

Absorption area of a soil dispersal system      
  average flow greater than 10,000 gallons/day 300   feet1
  serving a facility handling infectious or pathological wastes 150   feet1
  average flow 10,000 gallons/day or less 50   feet1
Agricultural chemical    
  tank or container with 25 gallons or more or 100 pounds or more dry weight, or equipment filling or cleaning area without safeguards 150   feet
  storage or equipment filling or cleaning area with safeguards 100   feet
  storage or equipment filling or cleaning area with safeguards and roofed 50   feet
  buried piping 50   feet
  multiple tanks or containers for residential retail sale or use, no single tank or container exceeding, but aggregate volume exceeding 56 gallons or 100 pounds dry weight 50   feet
Anhydrous ammonia tank 50   feet
Animal    
  feedlot, unroofed, 300 or more animal units 100   feet1
  feedlot, more than 1.0, but less than 300 animal units 50   feet1
  building or poultry building, including a horse riding area, more than 1.0 animal unit 50   feet1
  rendering plant 50   feet
  feeding or watering area within a pasture, more than 1.0 animal unit 50   feet1
  area to bury more than one animal unit 50   feet
  building, feedlot, confinement area, or kennel, 0.1 to 1.0 animal unit 20   feet1,2
       
Building, building projection, deck, overhang, permanent structure 3   feet3
       
Cesspool 75   feet1
Cistern or reservoir, buried, nonpressurized water supply 20   feet
Commercial compost site 50   feet
Construction or demolition debris disposal area 50   feet1
Cooling water pond, industrial 50   feet1
       
Deicing chemicals, bulk road 50   feet1
Drainfield (see Absorption area)      
Dry well (sewage) 75   feet1
       
Electric transmission line 10   feet4
Electrical transformer storage area, oil-filled 50   feet
Elevator boring, not conforming to rule 50   feet
  conforming to rule 20   feet
       
Fertilizer chemigation tank, safeguarded, from irrigation well only 20   feet5
Floor drain, grate, or trough    
  connected to a buried sewer 50   feet
  if buried sewer is air-tested, approved materials, serving one building, or two or less single-family residences 20   feet2
Frost-proof yard hydrant or discharge of a frost-proof hydrant draining into the soil,    
  fire hydrant or flushing hydrant 10   feet
       
Gas (flammable or volatile) pipe 10   feet4
Grave or mausoleum 50   feet
Gravel pocket or French drain for clear water drainage 20   feet
Gray-water dispersal area 50   feet1
       
Hazardous substance    
  tank or container, above ground or underground, 56 gallons or more, or 100 pounds or more dry weight, without safeguards 150   feet
  tank or container, above ground or underground, 56 gallons or more, or 100 pounds or more dry weight with safeguards 100   feet
  buried piping 50   feet
  multiple storage tanks or containers for residential retail sale or use, no single tank or container exceeding 56 gallons or 100 pounds, but aggregate volume exceeding 50   feet
Horizontal ground source closed loop heat exchanger buried piping 50   feet
Horizontal ground source closed loop heat exchanger buried piping and horizontal piping, approved materials and heat transfer fluid 10   feet2
Household solid waste disposal area, single residence 50   feet1
       
Interceptor, including a flammable waste or sediment 50   feet
       
Land spreading area for sewage, septage, or sludge 50   feet1
Landfill or dump, mixed municipal solid waste from multiple persons 300   feet1
Landfill, permitted demolition debris 300   feet1
Leaching pit 75   feet1
Liquid propane (LP) tank 10   feet4
       
Manure (liquid) storage basin or lagoon    
  unpermitted or noncertified 300   feet1
  approved earthen liner 150   feet1
  approved concrete or composite liner 100   feet1
Manure (solid) storage area, not covered with a roof 100   feet1
       
Ordinary high water level of a stream, river, pond, storm water retention pond, lake, or reservoir 35   feet2
       
Petroleum    
  tank or container, 1100 gallons or more, without safeguards 150   feet
  tank or container, 1100 gallons or more, with safeguards 100   feet
  tank or container, buried, between 56 and 1100 gallons 50   feet
  tank or container, not buried, between 56 and 1100 gallons 20   feet6
  buried piping 50   feet
Petroleum or crude oil pipeline to a refinery or distribution center 100   feet
Pit or unfilled space more than four feet in depth 20   feet
Pollutant or contaminant that may drain into the soil 50   feet1
Privy, nonportable 50   feet1
  portable (privy) or toilet 20   feet2
       
Sand filter, watertight; peat filter; or constructed wetland 50   feet
Scrap yard 50   feet
Seepage pit 75   feet1
Septic tank 50   feet
Sewage holding tank, watertight 50   feet
Sewage sump    
  capacity 100 gallons or more 50   feet
  capacity less than 100 gallons, tested, conforming to rule 20   feet2
Sewage treatment device, watertight 50   feet
Sewer, buried    
  collector, municipal, serving a facility handling infectious or pathological wastes, open-jointed or unapproved materials 50   feet
  approved materials, tested, serving one building, or two or less single-family residences 20   feet2
Solid waste transfer station 50   feet
Storm water drain pipe, 8 inches or greater in diameter 20   feet2
Swimming pool, in-ground 20   feet
       
Unused, unsealed well or boring 50   feet
       
Vertical heat exchanger (vertical) piping, conforming to rule 35   feet2
  horizontal piping conforming to rule 10   feet2
       
Wastewater rapid infiltration basin, municipal or industrial 300   feet1
Wastewater spray irrigation area, municipal or industrial 150   feet1
Wastewater stabilization pond    
  municipal, 500 or more gallons/acre/day of leakage 300   feet1
  municipal, less than 500 gallons/acre/day of leakage 150   feet1
  industrial 150   feet1
Wastewater treatment unit tanks, vessels and components (Package plant) 100   feet
Water treatment backwash disposal area 50   feet1
Water treatment backwash holding basin, reclaim basin, or surge tank    
  with a direct sewer connection 50   feet
  with a backflow protected sewer connection 20   feet
       
       
 

Additional Isolation Distances For

   

 

 

Community Public Water-Supply Wells

   

 

Highest water or flood level 50   feet
Property line, unless legally controlled through an easement 50   feet

 


1 A sensitive water-supply well must be located at least twice the indicated distance.

A sensitive water-supply well is a well with less than 50 feet of watertight casing, and which is not cased below a confining layer or confining materials of at least 10 feet in thickness.
2 A community public water-supply well must be a minimum of 50 feet from this contamination source.
3 A well or boring may not be constructed inside a building except as provided for by Minnesota Rules, part 4725.2175.
4 A well or boring may be located between 5 and 10 feet of an electric transmission line, gas pipe or LP tank if the well or boring is placarded, and work is not performed on the well or boring unless the electric line is deenergized and grounded or shielded, and the LP tank does not contain flammable gas.
5 The 20-foot distance applies only to an irrigation well and a fertilizer chemigation supply tank meeting the requirements of Minnesota Rules, Chapter 1505.
6 The 20-foot distance applies only to an irrigation well and a fertilizer chemigation supply tank meeting the requirements of Minnesota Rules, Chapter 1505.
Questions?
Contact the MDH Well Management Section
651-201-4600 or 800-383-9808
health.wells@state.mn.us

Minnesota Department of Health
Updated Tuesday, 31-Dec-2013 10:22:10 CST